1. To act in reckless disregard.
2. A form of permission.
3. A suggested course of action.

"Give'er Terry, give'er, give'er, give'er!"
This will work if:
1. Terry is about to do something reckless and is being egged on by friends who are encouraging him to continue/begin this action regardless of the consequences.
2. Terry asks if he can get a beer from the fridge. (typically reduced to one "give'er" instead of the above multiple "give'er's"
3. Terry asks you if its a good idea to ask out that good looking woman he sees.